The invention relates to a tool support for tool holders of rotationally driven tools which can be driven via a gear wheel arranged on one side of the tool holder and mounted for rotation about a gear wheel axis, comprising a receiving means provided on the tool support for at least one tool holder and a first toothed ring provided on the tool support and movable about a toothed ring axis so as to turn on a first path, wherein the first path has a first area of engagement nearest to the gear wheel axis for the gear wheel on the tool holder side.
Tool supports of this type are known from EP 0 799 663; with them the gear wheel of the tool holder is driven via a toothed ring arranged in the tool support.
As a result, there is no possibility with respect to the gear unit formed by the toothed ring and the gear wheel of adapting the transmission ratios in the case of different rotational speeds and torques.
For this reason, additional gear units have so far been provided within the tool holder and these were unstable, on the one hand, on account of the constructional size available and, in addition, involved additional flank clearance and thus inaccuracies with respect to the rotary position of the tool.
The object underlying the invention is therefore to improve a tool support of the generic type in such a manner that an adaptation of the transmission ratios can be realized in a simple manner.
This object is accomplished in accordance with the invention, in a tool support of the type described at the outset, in that a second toothed ring movable about the toothed ring axis so as to turn on a second path is provided on the tool support, that the second path has a second area of engagement nearest to the gear wheel axis for a gear wheel on the tool holder side, this area of engagement extending at a greater radial distance from the gear wheel axis than the first area of engagement and being located closer to the tool holder in the direction of the gear wheel axis than the first area of engagement.
A simple possibility is created with the inventive solution of making various transmission ratios available for the drive of the tool holders without the number of gear wheels required being increased.
In addition, this solution is extremely stable since a constructional space is available for the gear wheel on the tool side and the toothed rings which is greater than the constructional space available in a tool holder.
In principle, it would be conceivable to drive the first toothed ring and the second toothed ring by means of separate drives and thus create additional possibilities for variation with respect to the drive of the tool.
It has, however, proven to be particularly favorable with a view to a simple and stable solution when the first toothed ring and the second toothed ring can be driven by the same drive.
It is simplest from a constructional point of view and sufficient for operation when the first toothed ring and the second toothed ring are arranged on a drive wheel unit driven uniformly so that the two toothed rings rotate together. This simplifies, in particular, the provision of bearings for the toothed rings which can both therefore be mounted via a common bearing.
It has proven to be particularly favorable in this respect when the drive wheel unit is seated on a common shaft and mounted in the tool support via this.
A particularly simple construction of such a drive unit provides for the drive wheel unit to comprise two drive gear wheels connected to one another, wherein each one of the drive gear wheels bears one of the toothed rings.
One possibility of arranging the first and the second toothed rings and the gear wheels on the tool holder side is for the gear wheel axis to extend transversely to the toothed ring axis.
With respect to the design of the drive gear wheels and the gear wheels on the tool holder side, no further details have so far been given. It would, in principle, be conceivable to use bevel gears.
One expedient solution does, however, provide for at least one toothed ring to be designed as a toothed ring of a crown wheel and the corresponding gear wheel on the tool holder side as a cylindrical pinion. This solution has the advantage that such a cylindrical pinion is positionally unsusceptible with respect to its relative position in a radial direction to the crown wheel, as a result of which all the tolerance problems with respect to the radial position of its gear wheel determined by the tool holder can be avoided in a simple manner.
It is particularly favorable when both toothed rings are designed as a toothed ring of a crown wheel and the respectively corresponding gear wheels on the tool holder side as cylindrical pinions.
A further possibility for arranging the gear wheels and the toothed rings is for the gear wheel axis to extend parallel to the toothed ring axis.
In this case, it is preferably provided for the toothed rings to be designed as toothed rings of spur wheels and for the gear wheels on the tool holder side to be cylindrical pinions.
One advantageous variation provides for the first toothed ring and the second toothed ring to have the same number of teeth but different moduli so that, as a result, it is possible to select transmission ratios in a simple manner in accordance with the size of the gear wheels on the tool holder side.
In principle, an inventive tool support could be designed such that it has one receiving means for a tool holder. It is, however, particularly advantageous when the inventive tool support has at least two receiving means for tool holders and for not only the first toothed ring but also the second toothed ring to be arranged in the tool support such that with them a drive of a first and second gear wheel, respectively, of a tool holder arranged in the first receiving means and/or of a tool holder arranged in the second receiving means can be realized.
It is particularly favorable when the receiving means for the tool holders have such a distance from one another that the second gear wheels on tool holders arranged in both receiving means are rotatable free from collision.
A particularly advantageous solution of an inventive tool support provides for this to have a plurality of receiving means for tool holders arranged in azimuthal direction around the toothed ring axis.
In addition, the invention relates to a tool assembly for rotationally driven tools of machine tools, comprising a tool holder for the rotationally driven tool with a tool holder housing, in which a tool spindle is rotatably mounted which can be driven by a gear wheel on the tool holder side, this gear wheel being arranged on one side of the tool holder housing and mounted for rotation about a gear wheel axis, wherein, in accordance with the invention, the tool support is designed in accordance with any one of the preceding embodiments.
The advantage of the inventive solution is thus the same as that explained in conjunction with the inventive tool support.
With respect to the type of drive for the tool holders, different solutions are conceivable. For example, it would be conceivable to drive two gear wheels on the tool holder side with the two toothed rings and thus also have the possibility of using different rotational speeds at the tool holder.
One solution which is particularly advantageous with respect to the simplicity and operational safety provides for the tool holder either to be provided with a first gear wheel which can be brought into engagement with the first toothed ring or to be provided with a second gear wheel which can be brought into engagement with the second toothed ring so that different transmissions for the drive of the tool spindle can be realized depending on the provision of a first or a second gear wheel on the tool holder.
A particularly advantageous solution provides for the gear wheels arranged on the tool holder to be interchangeable with one another so that a first gear wheel can be interchanged for a second gear wheel and a second gear wheel for a first gear wheel so that an adaptation to the desired transmission ratio for the drive of the tool spindle is possible by changing the gear wheels dependent on the particular use.
This can preferably be realized in that not only the first gear wheel but also the second gear wheel can be fixed interchangeably on a tool drive shaft coupled to the tool spindle.
The inventive solution may then be utilized particularly favorably when the tool drive shaft is provided at its end facing away from the tool holder with a coolant supply connection which is connected to a connection receiving means arranged on the tool support when a tool holder is fixed in the receiving means.
A particularly favorable solution provides for the coolant supply connection to be designed as a coolant transfer pin and thus to be rotatable in a simple manner with the tool shaft in relation to the coolant connection receiving means whereas the coolant connection receiving means is arranged so as to be stationary.
In principle it would be conceivable for the tool drive shaft to drive the tool spindle in the tool holder via an additional gear element. A particularly favorable solution does, however, provide for the tool drive shaft to be arranged coaxially to the tool spindle.
It is preferably provided, in particular, with such a solution for the tool drive shaft and the tool spindle to be penetrated by a common coolant channel which leads from the coolant supply connection to the tool.
Additional features and advantages of the invention are the subject matter of the following description as well as the drawings illustrating several embodiments of the invention.